Thanks, but for some reason that still allowed the ads to play before the video contents started though.
I finally found a filter that does allow the video while still blocking the ads playing before it.

!Filter for player on vtm.be
@@||fwmrm.net/ad/g/$xmlhttprequest,script,domain=vtm.be
!Filter for embedded player (working on nieuws.vtm.be, not working on hln.be)
@@||fwmrm.net/ad/g/$xmlhttprequest,script,domain=player.medialaancdn.be

Edit: Got it working for hln.be now too, needed syndication.medialaan.be in the filter.

!Filter for player on vtm.be
@@||fwmrm.net/ad/g/$xmlhttprequest,script,domain=vtm.be
!Filter for player on nieuws.vtm.be
@@||fwmrm.net/ad/g/$xmlhttprequest,script,domain=player.medialaancdn.be
!Filter for player on hln.be
@@||fwmrm.net/ad/g/$xmlhttprequest,script,domain=syndication.medialaan.be